Truing mechanism for grinding machines



y .3 1932- H. M. ALLISON 1,856,180

TRUING MECHANISM FOR GRINDING MACHINES Filed May 21, 1930 3 Sheets-Sheet 1 May 3, 1932. H. M. ALLISON TRUING MECHANISM FOR GRINDING MACHINES Filed May 21, 1930 5 Sheets-Sheet May 3, 1932. H. M. ALLISON TRUING MECHANISM FOR GRINDING MACHINES 77/275412 A62 qyWAldmvn.

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I It is the object of my invention to along the line 3-3 in Patented May 3, 1932 UNITED STATES HABVIEY I. ALLISON, O]? WORCESTER, MASSACHUSETTS, ASSIGNOR OF WORCESTER, MASSACHUSETTS ATsNroFncs 'rmrnre Humanism m GRINDING macnmns .lpplioation fled Kay 21 1930. Serial No. 454,461.

This invention relates to mechanism for truing the cutting edge of a grinding wheel for use in a thread grinding or other similar machine. It is of great importance in such operations that the edge portion of the grind ing wheel be very accurately shaped to a predetermined cutting section. 1

provide an improved mechanism for trui-ng the edge portion of a grinding wheel to a predetermined section.

More-specifically, I provide mechanism for producing the side faces of a grinding wheel at predetermined angles to the plane of the wheel and I also provide means for shaping the extreme-outer edge of the wheel to a desired arc.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. l is a side elevation of my truing mechanism;

Fig. 2 is a sectional plan View, the line 22 in Fig. l;

Fig. 3 is a sectional Efront elevation, taken Fig. 4 is a detail view to be described;

Fig. 5 is an enlarged sectional front elevation, taken along the line 55 in Fig. 1;

Figs. 6 and 7 are detail sectional side elevations, taken along the lines 6-6 and 77 in Fig. 5;

Fig. 8 is a detail sectional plan view, taken along the line 8-8 in Fig. 5;

Figs. 9 and 10 are detail views of certain parts to be described;

Fig. 11 is a sectional plan view, taken along improved taken along the line ii -ii in Fig. 1;

Fig. 12 is a detail side elevation, looking in the directionof the arrow 12in Fig. 11; and

Figs. l3, 14, 15 and 16 are diagraimnatic,

views illustrating the operation of my improved mechanism.

Referring particularly to Fi 1 to 4; I have shown a grinding wheel mounted on a wheel shaft 20 and rotated athigh speed by suitable driving mechanism, not shown.

The wheel shaft 20 is rotatable in hearings on a wheel head 21 (Fig. 1) having a dovetailed guideway 22 secured tothe side face thereof. A slide 23 is mounted on the guide,-

520 JOHN urn, 1

way 22 and is held in position thereon b a gib 24. An adjusting screw 25 is rotata la in a bearing 26 at the outer end of the member 22 but is held from axial movement therein by a flange 27.

The screw 25 is threaded into a nut 28 on the slide 23. The screw is provided with a. ratchet wheel 29 and with a handle 30 by which the screw may be rotated. A pawl 31 engages the ratchet 29 and prevents reverse movement thereof until the pawl is released.

A frame or bracket 33 is mounted on the side of'the slide 23 and is secured thereto by bolts 34. It is sometimes desirable to mount the frame 33 at an angle to the slide 23 corre sponding to the pitch of the helix to be eaf ground. Accordingly I provide a wedge36 (Figs. 3 and 4) adapted to be interposed be-' tween the frame or bracket 33 and the slide 23. The wedge 36 is preferably formed with an upward and offset extension 37 in which an adjusting screw 38 is rotatably mounted but held from axial relative movement. The screw 38 is threaded in the upper edge of the slide 23 and by turning the screw 38 the wedge 36 may m raised or lowered, thus providing a slight but veryaccurate adjustment of the bracket 33 axially of the grinding wheel.

The Wedge 36 is formed with slots 39 to re 'ceive the bolts 34, permitting longitudinal adjustment of the wedge.

A frame member 40 (Figs. 1 and 5) is pivoted in upper and lower bearings 41 and 42 projecting laterally from the bracket 33. Theframe member 40 is formedwith-an open center portion, as clearly shown in Fig. 5. and is prov ded with bearings 44 for a trans ver'sely slidableshaft45 which is preferably of rectangular or non-circular cross section.

Qne end of the shaft 45 is connected by'a link 47 (Fig. 8) to an eccentric stud 48 (Fig. 9) formed on the lower end of a short shaft 50. The shaft 50 is rotatable in a bushing 51 58 in the bearing 56 forces the ingly into end of the bracket 52.

A handle 61 projects upward from the cross arm 55 and a release lever 62 is mounted alongside the handle 61 and engages a cross pin 63 in the outer end of the latch 57. When the latch 57 is seated in the notch 60, the sliding shaft 45 is held in mid-position,

but after the latch is withdrawn by pressure 7 f on the release lever 62, the eccentric stud 48 middle portion of the may be moved angularly to give the shaft 45 a short sliding or reciprocating movement.

A diamond point or other wheel dressing tool 70 (Fig. 6) is mounted in a tool holder 71 which is slidable toward and from the wheel W in a bearing 7 2 in the upper portion of a tool support 73 which is clamped to the sliding shaft 45.

An adjusting screw 74 is mounted for rotation in a bearing plate 75 secured to the support 73 but is held from axial movement in said plate by a flange 76 on the screw and a head 77 secured thereto. The head 77 (Fig. 11) is knurled so that it may be conveniently turned manually and is also provided with graduations 78, there being a corresponding zero mark 79 on the top of the bearingplate An arm 80 (Fig. 5) is secured to a lower portion of the frame 40 and is provided with a handle 81. A segmental plate 82 (Fig. 11) I is mounted on the frame 33 and is provided 5 with segmental slots 83 to receive threaded studs 84 (Fig. 12) projecting downward from stops 85. Nuts 86 are threaded on the studs 84 and provide means for firmly securing the stops in adjusted position.

Each stop 85'has an upwardly projecting lug 87 positioned for engagement by the arm- 80 previously described. The stops 85 may be set to limit the swinging'movement of the frame 40 in both directions.

Having described the details of construction of my improved truing mechanism, the method of using the same is as follows:

The tool support 73 (Fig. 6) is adjusted on the sliding shaft 45 by means of a clampingscrew 90 in such a position that the point of the tool is in a plane substantially transverse to the axis of the grinding wheel and passing through the pivotal axis of the frame 40. This plane may be inclined from the vertical to correspond to the angle of the helix, such inclination being produced by use of the wedge 36.

After approximate adjustment has been secured as above described, a slight correccurvature of the extreme outer edge of the wheel.

The stops 85 are then adjusted to limit the swinging movement of the frame 40 to such positions that the sliding movement of the cross shaft 45 will be in the desired angular relation to the plane of the wheel W.

After the device is thus set, the truing of the wheel proceeds as indicated in Figs. 13, 14 and 15. The frame 40 is swung around against one of the stops 85 and the tool 70 is then reciprocated by means of the handle 61 andsliding shaft 45, as indicated in Fig. 13, thus accurately dressing and truing one side portion of the wheel W.

The tool 70 is then brought to mid-position and locked by the latch 57, after which the frame 40 is swung on its pivots in its bearings 41 and 42, causing the point of the tool 70 to describe an are around the edge of the wheel WV and to produce an edge of corresponding curvature thereon.

The frame 40 is then swung around to the position determined by the second stop 85' and the opposite side portion of the cutting edge is then dressed andtrued. In this way. a cutting edge having side faces at a predetermined angle and having an extreme outer edge portion of predetermined curvature is readily produced. Such a section in a grinding wheel is desirable and necessary in producing certain kinds of work,,such as a (hitworth screw thread.

-By rounding. the end of the tool 70, as indicated at 70 in Fig. 16, I may also form concave surfaces at the inner ends of the cut ting faces of the wheel.

In this case, I provide stop screws 90 (Fig. 5) by which sliding movement of the tool 70 may be limited and the concave surfaces may be definitely located. v

It will thus be seen that I have provided a very simple mechanism by which a grinding wheel may be trued up to provide side faces at desired angles and to provide an extreme edge portion of desired curvature and also an occasion to provide desired curvatures at the base of the cutting portion of the wheel.

Having thus described my invention and the advantages thereof, I 'do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what 1. Truing mechanism for a grinding inachine having a rotatably mounted grinding wheel comprising a slide, a supporting frame the axis and at a desired having an open center and mounted-thereon to swing about a substantially vertical axis transverse to the axis of the grinding wheel, said frame having supportin bearings sub- U stantially above and below the axis of the grinding wheel and having the portion between the bearings ofl'set away from the grindin wheel and beyond the vertical axis of said rame, a wheel dressing tool slidably is mounted in said frame and supported in front of the vertical axis of said frame, means to swing said frame to dress the segmental cutting edge of said wheel, and means to reciprocate said tool in said frame to dress the 15 sides of the edge portion of said wheel.

2. Truing mechanism for a grinding machine having a rotatably'mounted grinding wheel, comprisin a supporting frame mounted to swing a out a su stantially verti- V so cal axis transverse to the axis of the grinding wheel, a wheel dressing tool, a slide on which said tool is mounted, said slide-being movable in guideways on said supportin frame and transverse to the axis thereo 25 means to reciprocate said slide in said guideways, and means to lock said slide in predetermined mid-position in said guideways.

3. In a grinding machine, a grinding wheel, a wheel head, a. slide movably mount-' ea ed on said wheel head, means to move said slide toward and from the axis of the wheel, a supporting frame mounted to swing on said slide and having an open center portion, a wheel dressing tool mounted for transverse 35 reciprocation in said open ,center portion, means to reciprocate said tool in said frame across a face of the grinding wheel, and means to adjust said tool toward and from the wheel said adjusting means extending 0 through the open center ofthe supporting frame to a position readily accessible by the operator.

4.. The combination in a inding machine as setforth in claim 3, in'w ich means is pro- 45 vided for limiting the sliding movement of I paid wheel dressing tool to a predetermined ocus.

In testimony whereof I have hereunto affixed my signature.

k -HARVEY M. ALLISON. 

